\psset{unit=0.5,yunit=0.8, algebraic=true, ticksize=-3pt 0, linewidth=0.8pt}
\begin{pspicture*}(-1,-1)(10,10)
\footnotesize
\psaxes[arrows=<->,ticks=none](0,0)(-1,-1)(10,10)
\psplot[linecolor=blue]{0}{3.8}{1/(x-4)+5}
\psplot[linecolor=blue]{4.1}{10}{1/(x-4)+5}
\psline[linecolor=red](0,5)(10,5)
\psline[linecolor=red](4,0)(4,10)
\psxTick(4){a}
\psyTick(5){b}
\rput[r](10,4.5){Asíntota horizontal}
\rput[r](10,3.5){$y=b$}
\rput[l](4.2,1.5){Asíntota vertical}
\rput[l](4.2,0.5){$x=a$}
\end{pspicture*}


